﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.Windows;

namespace VolumeMaster {

	public sealed class Taskbar {
		private const string ClassName = "Shell_TrayWnd";

		public Rectangle Bounds {
			get;
			private set;
		}
		public TaskbarPosition Position {
			get;
			private set;
		}
		public Point Location {
			get {
				return this.Bounds.Location;
			}
		}
		public Size Size {
			get {
				return this.Bounds.Size;
			}
		}

		public bool AlwaysOnTop {
			get;
			private set;
		}
		public bool AutoHide {
			get;
			private set;
		}

		public Taskbar() {
			IntPtr taskbarHandle = User32.FindWindow(Taskbar.ClassName, null);

			APPBARDATA data = new APPBARDATA();
			data.cbSize = (uint)Marshal.SizeOf(typeof(APPBARDATA));
			data.hWnd = taskbarHandle;
			IntPtr result = Shell32.SHAppBarMessage(ABM.GetTaskbarPos, ref data);
			if (result == IntPtr.Zero)
				throw new InvalidOperationException();

			this.Position = (TaskbarPosition)data.uEdge;
			this.Bounds = new Rectangle(data.rc.left, data.rc.top, data.rc.right, data.rc.bottom);

			data.cbSize = (uint)Marshal.SizeOf(typeof(APPBARDATA));
			result = Shell32.SHAppBarMessage(ABM.GetState, ref data);
			int state = result.ToInt32();
			this.AlwaysOnTop = (state & ABS.AlwaysOnTop) == ABS.AlwaysOnTop;
			this.AutoHide = (state & ABS.Autohide) == ABS.Autohide;
		}
	}

	public enum ABM : uint {
		New = 0x00000000,
		Remove = 0x00000001,
		QueryPos = 0x00000002,
		SetPos = 0x00000003,
		GetState = 0x00000004,
		GetTaskbarPos = 0x00000005,
		Activate = 0x00000006,
		GetAutoHideBar = 0x00000007,
		SetAutoHideBar = 0x00000008,
		WindowPosChanged = 0x00000009,
		SetState = 0x0000000A,
	}

	public enum ABE : uint {
		Left = 0,
		Top = 1,
		Right = 2,
		Bottom = 3
	}

	public static class ABS {
		public const int Autohide = 0x0000001;
		public const int AlwaysOnTop = 0x0000002;
	}

	public static class Shell32 {
		[DllImport("shell32.dll", SetLastError = true)]
		public static extern IntPtr SHAppBarMessage(ABM dwMessage, [In] ref APPBARDATA pData);
	}

	public static class User32 {
		[DllImport("user32.dll", SetLastError = true)]
		public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
	}
	
	public struct Rectangle {
		public Size Size;
		public Point Location;
		public Rectangle(int x, int y, int x2, int y2) {
			Location = new Point(x, y);
			Size = new Size(x2 - x, y2 - y);
		}
	}

	[StructLayout(LayoutKind.Sequential)]
	public struct APPBARDATA {
		public uint cbSize;
		public IntPtr hWnd;
		public uint uCallbackMessage;
		public ABE uEdge;
		public RECT rc;
		public int lParam;
	}

	[StructLayout(LayoutKind.Sequential)]
	public struct RECT {
		public int left;
		public int top;
		public int right;
		public int bottom;
	}

	public enum TaskbarPosition {
		Unknown = -1,
		Left,
		Top,
		Right,
		Bottom,
	}
}
